Means for ascertaining elevations of aircrafts



Oct- 13, 1925- E. N. TODD MEANS FOR ASCER-TAINING ELEVATIONS OF AIRCRAFTS 1925 2 Sheets-Sheet l Filed March 16 I EZhr a/V. 154d INVENTOR ATTORNEY WITNESS:

Oct. 13, 1925. 1,557,389

E. N. TODD MEANS FOR ASCERTAINING ELEVATIONS 0F A'IRcRAFTs v Filed March 16 1925 2 Sheets-Sheet 2 7 1 1K932. F g. 3. A?

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i I f7 70 4 W I Q I z/ I l I ZZ a Z6 .EZerz N. Todd WITNESS: ATTORNEY INVENTOR Patented Oct. 13, 1925 i mus FOR ,Ascnn'rnmmc ELEVATIONS or Amounts] Application flied March 16, 1925. Serial No. 16,072. i

. of Maryland, have'invented new' and useful Improvements in Means for. Ascertaiuing Elevations of Aircrafts, of which the fol lowing is a specification.

This invention relates to height finders for aircrafts and has forits object theprovision of novel means designed to be set in "action'by the pilot or other occupant of an 'lngs, the device is shown asincluding a casaeropla'ne or the like whereby the height of the plane or other craft, above the surface of the earth may be definitely ascertained, regardless of whether the flying be done by -day of by night and'also in case the craft be travelling above the clouds.

An important object is the provision of 2 an apparatus'pof this character which embodies means for' sending out a radio wave at the surface of the earth, which wave may consequently be received in a suitable receiving apparatus carried by the aircraft.-

A more specificobject is the provision of an apparatus of this character including a device for sending out a radio wave, the device being enclosed within a suitable housing and being adapted to be dropped overboard ;trom the aircraft, the construction and arrangement being such that upon striking the surface of the earth or the surface of a body of water the mechanism will be. operated to send out a radio wave which may be received by means of suitable apparatus in thecraft, the time interval elapsing between the moment of dropping the device overboard and the moment of re- ,ceiving thesignal forming part of a calculation or" being used in making calculations which will definitely dis'close'the'exact 1 height ofth'e'cr'aft above, the surface offt'he earth.. p

Another object is the provision of a device'of this character which may be made comparatively inexpensively, which is easy tooPerate and control, positive in action,

'eificient and durable in service, and a general improvement in the art.

With the above and other objects and advantages in view, the invention consists in the details of construction to be hereinafter more fully described and claimed, andilluswhich:

trated in the accompanying drawings n Figure 1 is a side elevation'fof'the device intended to be dropped overboard; Figure 2 is alongitudinal section there'- through, V Figure 3 is a longitudinal sectionv taken at right angles to Figure 2,'

Figure 4 is a bottom plan view, and: Figure 5 is a diagram of the electrical cir- 'cuit in the transmitting apparatus. Referring more particularly to the draw,-

ing or housing 10 within which is enclosed the radio transmitting apparatus to'be 'described.

It is preferable to provide a parachute 11 carrying a suitable insulator 12'from which is suspended a wire 13 connected with the "housing or casing '10 and constituting an,

aerial or antenna.v Suspended and insulat ed from the bottom of the casing or housing 10 is a ground wire 14, insulated as shown at '1'5 and preferably carryi g a weight '16 1 which will maintain the wire taut.

Mounted'within the casing or housing 10 is any preferred or suitable type of radio transmitting apparatus which might be of the spark or continuous wave variety, such details being immaterial though it is naturally preferable that the apparatus be inexpensive in view of the fact thatafterit is used once it-is forever destroyed and"consequently entirely useless.

For the sake of illustration I have 'dis closed the transmitting apparatus as being of the spark type and includinga conven tionalinductaucecoil 17 having a primary coil 18, 'a secondary coil 19 and-the usual vibrator 20. The inductance coil is adapted to be energized by means of any suitable Lsource ofcurrent 21 which may be a plu-Y rality of dry batteries as indicated inFigure 3, though it is obvious that a storage battery or the like mi ht be used if ,pre- 'ferred for any reason w atsoeve'r. The pri mary" and secondary coils 18' and'19'a1ie 100 shownas thoserbeing connected at one end with a conductor 21 connected with a. stationary support 22 at the bottom of the easing or housing 10, which support has p1voted thereon, at 23, a contact arm 24 nor- 105 mally out of engagement withbut adapted PATEN FiYeTE EL 1m n! 1v. mom), or cnrsrmnn, mnvnnun. a

to engage against a, contact, 25 which is likewise mounted at the bottom of the cas-v ing or housing. A coil spring 26 may be provided connected with the contact arm 24 for the purpose of normally urging it toward the contact 25. The above described insulator is suspended from the contact arm. 24,50 that the weight thereof combined with the weight of the wire 14 and the ball or the like 16 will normally hold the contact arm 24-0ut of engagement with the contact 25, in opposition to the tension of the spring 26. Also connected with the wire 21 is a conductor 27 -..which connects with the ound wire 14 at a point below the insuator 15. One terminal of the source'of current is connected by a conductor 28 with the contact 25 while the other terminal of the source of current is connected by a "conductor 29 with the stationary contact 30 of the vibrator structure. The other terminal of the primary coil 19 is connected. with the vibrator arm while the remaining terminal of the secondary coil is connected with the wire 13 which constitutes the aerial or antenna. A suitable spark gap 31 is inte d between the conductors 21 and 13 so t at when the inductance coil is energized upon closing of the circuit-through the primary thereo a spark will pass across the ga .31 and of course send out waves from t e aerial.

In the use of the device, it is apparent that it must of course be carried in the aircraft and so arranged or disposed that the contact arm 24 wil be out of engagement with the contact 25. Whenever it is desired to ascertain the height of the aircraft above the surface. of the earth, the entire device must be thrown overboard or dropped a note being made as to the exact time. (jf course, the parachute will open and the device will descend-at a more or less rapid rate until it strikes the surface of the ground or the surface of a body of water, as the case may be. The moment that the wei ht 1B strikes against the ground or the 'su ace of the water it is obvious that the pull upon the contact arm '24 will be relieved so that the spring 26 may act to swing the arm 24 into engagement with the contact 25. When this occurs the circuit is com leted through the primary coil of the in uction coil and the source of current. A high potential current is of course induced in the secondalz coil in a well kliliown manner and a spar will jump across t e a tram of waves which will r iate from the wire 13 constituting the aerial or antenna.

In case the device drops upon water the:

wire 14 will act as a ground wire and if the device should drop upon solid ground gap 31, resulting 1n the roduction of this same'wire will act in substantially the same manner in view of the fact that it will constitute a counterpoise. It will thus be seen that the instant the device strikes the surface of the earth,radio waves are sent out. -It is of course intended that the aircraft be equipped with some suitable type of receiving apparatus by means of which these waves may be received, the time of reception being noted. When the time interval between the dropping of the device and the race tion is known, it isapparent that calculatlons may be made to ascertain the height of the aircraft in a very simple and ea manner as the feed of the text of the device is readily ascertainable or computable. Having this data it is evident that reference may be had to a suitable chart and in this way the exact elevation of the plane or other craft may be known. While I have shown and described the preferred embodiment of the invention, it should be understood that I reserve the right to make such changes in the form, construction and arran ement of parts as will not depart from the spirit of the invention or t e scope .of the snbjoined' claims. Having thus described the. invention, I claim: 1. In an apparatus of the character described, the combination of a radio receiving apparatus, a portable radio transmitting apparatus adapted to be dropped, and impact operated means for controlhng the energization of the transmitting mechanism.

2. In elevation finder. for aircrafts, the

combination of a receiving aparatus adapted to be carried upon the aircraft, a portable radio transmitting a paratus adapted to be dropped overboard cm the aircraft, antenna and ground wires connected with said transmitting apparatus, means normally preventing operation of the transmittin a paratus, and earth impact release means or permitting operation of the transmitting ap aratus.

3. In a ei ht finder for aircrafts, the combination 0 a radio receiving apparatus carried by the aircraft, a transmitting a paratus adapted to be dropped from t e air craft, an aerial wire connected with the transmitting a paratus, a parachute from which the aeria wire is suspended, aground wire suspended from the transmitting apparatus, a normally open circuit controlled switch in the energlzin circuit of the transmitting apparatus a apted to beclosed upon impact with the earth whereby to close the circuit. I

In testimony whereof I ailix my signature.

ELBERT N. TODD. 

